This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. ABSTRACT: We see swirls in Drosophila flight muscle mitochondria in response to oxidative stress. 3D tomography is needed to see their detailed structure. Specifically, we want to know whether there are single or multiple cristae involved in swirl formation, how the swirl shape relates to the shape of normal cristae in these mitochondria, and whether the swirl cristae are attached to the peripheral region of the inner membrane (i.e. whether there are crista junctions). In the 2006-2007 reporting period, tissue blocks were received and sections were cut for HVEM tomography. Two single-tilt reconstructions were made. In the previous reporting period, this project represented the majority of the effort on service projects this year, carried out by Karolyn Buttle, amounting to almost two month's work. Dr. Mannella worked with Ms. Buttle in visualizing the tomographic data collected previously in order to faithfully represent and display the unique structures in these mitochondria. Many different methods were tried, and a variety of illustrations and animations were made for presentation and publication. New images and three new tomographic reconstructions were recorded, in an effort to collect different stages of swirl formation. Considerable effort was again spent on visualization of this data, yielding informative surface-rendered models and animations that were used in some of Dr. Mannella's presentations.